Electrochemical fuel cell stack with improved reactant manifolding and sealing

ABSTRACT

An electrochemical fuel cell stack with improved reactant manifolding and sealing includes a pair of separator plates interposed between adjacent membrane electrode assemblies. Passageways fluidly interconnecting the anodes to a fuel manifold, and interconnecting the cathodes to an oxidant manifold, comprise at least one fluid passageway formed between adjoining non-active surfaces of the pairs of separator plates. The passageways extend through one or more ports penetrating the thickness of one of the plates thereby fluidly connecting the manifold to the opposite active surface of that plate, and the adjacent electrode. The ports comprise walls that have surfaces that are angled more than 0 degrees and less than 90 degrees with respect to the direction of fluid flow in the fluid passageway upstream of the port. During operation, electrochemical fuel cell stacks comprising fluid ports with angled walls benefit from reduced pressure loss. Turbulence, which is believed to have adverse effects on the membrane electrode assemblies of solid polymer fuel cells, is also reduced.

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/471,564 filed Dec. 23, 1999, which is a continuation-in-partof U.S. patent application Ser. No. 09/116,270 filed Jul. 16, 1998. The'270 application in turn relates to and claims priority benefits fromU.S. Provisional Patent Application Ser. No. 60/052,713 filed Jul. 16,1997. The '564 and '270 applications, and the '713 provisionalapplication, are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

[0002] The present invention relates to electrochemical fuel cellstacks. In particular, the invention provides an electrochemical solidpolymer fuel cell stack with improved reactant manifolding and sealing.

BACKGROUND OF THE INVENTION

[0003] Electrochemical fuel cells convert reactants, namely, fuel andoxidant fluid streams, to generate electric power and reaction products.Electrochemical fuel cells employ an electrolyte disposed between twoelectrodes, namely a cathode and an anode. The electrodes generally eachcomprise a porous, electrically conductive sheet material and anelectrocatalyst disposed at the interface between the electrolyte andthe electrode layers to induce the desired electrochemical reactions.The location of the electrocatalyst generally defines theelectrochemically active area.

[0004] Solid polymer fuel cells typically employ a membrane electrodeassembly (“MEA”) consisting of a solid polymer electrolyte or ionexchange membrane disposed between two electrode layers. The membrane,in addition to being ion conductive (typically proton conductive)material, also acts as a barrier for isolating the reactant streams fromeach other.

[0005] The MEA is typically interposed between two separator plates thatare substantially impermeable to the reactant fluid streams. The platesact as current collectors and provide support for the MEA. Surfaces ofthe separator plates that contact an electrode are referred to as activesurfaces. The separator plates may have grooves or open-faced channelsformed in one or both surfaces thereof, to direct the fuel and oxidantto the respective contacting electrode layers, namely, the anode on thefuel side and the cathode on the oxidant side. Such separator plates areknown as flow field plates, with the channels, which may be continuousor discontinuous between the reactant inlet and outlet, being referredto as flow field channels. The flow field channels assist in thedistribution of the reactant across the electrochemically active area ofthe contacted porous electrode. In some solid polymer fuel cells, flowfield channels are not provided in the active surfaces of the separatorplates, but the reactants are directed through passages in the porouselectrode layer. Such passages may, for example, include channels orgrooves formed in the porous electrode layer or may just be theinterconnected pores or interstices of the porous material.

[0006] In a fuel cell stack, a plurality of fuel cells are connectedtogether, typically in series, to increase the overall output power ofthe assembly. In such an arrangement, an active surface of the separatorplate faces and contacts an electrode and a non-active surface of theplate may face a non-active surface of an adjoining plate. In somecases, the adjoining non-active separator plates may be bonded togetherto form a laminated plate. Alternatively both surfaces of a separatorplate may be active. For example, in series arrangements, one side of aplate may serve as an anode plate for one cell and the other side of theplate may serve as the cathode plate for the adjacent cell, with theseparator plate functioning as a bipolar plate. Such a bipolar plate mayhave flow field channels formed on both active surfaces.

[0007] The fuel stream that is supplied to the anode separator platetypically comprises hydrogen. For example, the fuel stream may be a gassuch as substantially pure hydrogen or a reformate stream containinghydrogen. Alternatively, a liquid fuel stream such as aqueous methanolmay be used. The oxidant stream, which is supplied to the cathodeseparator plate, typically comprises oxygen, such as substantially pureoxygen, or a dilute oxygen stream such as air.

[0008] A fuel cell stack typically includes inlet ports and supplymanifolds for directing the fuel and the oxidant to the plurality ofanodes and cathodes respectively. The stack often also includes an inletport and manifold for directing a coolant fluid to interior passageswithin the stack to absorb heat generated by the exothermic reaction inthe fuel cells. The stack also generally includes exhaust manifolds andoutlet ports for expelling the unreacted fuel and oxidant gases, as wellas an exhaust manifold and outlet port for the coolant stream exitingthe stack. The stack manifolds, for example, may be internal manifolds,which extend through aligned openings formed in the separator layers andMEAs, or may comprise external or edge manifolds, attached to the edgesof the separator layers.

[0009] Conventional fuel cell stacks are sealed to prevent leaks andinter-mixing of the fuel and oxidant streams. Fuel cell stacks typicallyemploy fluid tight resilient seals, such as elastomeric gaskets betweenthe separator plates and membranes. Such seals typically circumscribethe manifolds and the electrochemically active area. Applying acompressive force to the resilient gasket seals effects sealing.

[0010] Fuel cell stacks are compressed to enhance sealing and electricalcontact between the surfaces of the plates and the MEAs, and betweenadjoining plates. In conventional fuel cell stacks, the fuel cell platesand MEAs are typically compressed and maintained in their assembledstate between a pair of end plates by one or more metal tie rods ortension members. The tie rods typically extend through holes formed inthe stack end plates, and have associated nuts or other fastening meansto secure them in the stack assembly. The tie rods may be external, thatis, not extending through the fuel cell separator plates and MEAs,however, external tie rods can add significantly to the stack weight andvolume. It is generally preferable to use one or more internal tie rodswhich extend between the stack end plates through openings in the fuelcell separator plates and MEAs as, for example, described in U.S. Pat.No. 5,484,666. Typically springs, hydraulic or pneumatic pistons,pressure pads or other resilient compressive means are utilized tocooperate with the tie rods and end plates to urge the two end platestowards each other to compress the fuel cell stack components.

[0011] The passageways which fluidly connect each electrode to theappropriate stack supply and/or exhaust manifolds typically comprise oneor more open-faced fluid channels formed in the active surface of theseparator plate, extending from a reactant manifold to the area of theplate which corresponds to the electrochemically active area of thecontacted electrode. In this way, for a flow field plate, fabrication issimplified by forming the fluid supply and exhaust channels on the sameface of the plate as the flow field channels. However, such channels maypresent a problem for the resilient seal, which is intended to fluidlyisolate the other electrode (on the opposite side of the ion exchangemembrane) from this manifold. Where a seal on the other side of themembrane crosses over open-faced channels extending from the manifold, asupporting surface is required to bolster the seal and to prevent theseal from leaking and/or sagging into the open-faced channel. Onesolution adopted in conventional separator plates is to insert a bridgemember that spans the open-faced channels underneath the resilient seal.The bridge member preferably provides a sealing surface that is flushwith the sealing surface of the separator plate so that a gasket-typeseal on the other side of the membrane is substantially uniformlycompressed to provide a fluid tight seal. The bridge member alsoprevents the gasket-type seal from sagging into the open-faced channeland restricting the fluid flow between the manifold and the electrode.Instead of bridge members, it is also known to use metal tubes or otherequivalent devices for providing a continuous sealing surface around theelectrochemically active area of the electrodes (see, for example, U.S.Pat. No. 5,570,281), whereby passageways, which fluidly interconnecteach electrode to the appropriate stack supply or exhaust manifolds,extend laterally within the thickness of a separator or flow fieldplate, substantially parallel to its major surfaces.

[0012] Conventional bridge members are affixed to the separator platesafter the plates have been milled or molded to form the open-faced fluidchannels. One problem with this solution is that separate bridge membersadd to the number of separate fuel cell components that are needed in afuel cell stack. Further, the bridge members are typically bonded to theseparator plates, so care must be exercised to ensure that therelatively small bridge members are accurately installed and that thebonding agent does not obscure the manifold port. It is also preferableto ensure that the bridge members are installed substantially flush withthe sealing surface of the separator plate. Accordingly, theinstallation of conventional bridge members on separator plates addssignificantly to the fabrication time and cost for manufacturingseparator plates for fuel cell assemblies. Therefore, it is desirable toobviate the need for such bridge members, and to design anelectrochemical fuel cell stack so that the fluid reactant streams arenot directed between the separator plates and MEA seals.

SUMMARY OF THE INVENTION

[0013] In the present approach, passageways fluidly interconnecting ananode to a fuel manifold, or interconnecting a cathode to an oxidantmanifold, in an electrochemical fuel cell stack are formed between thenon-active surfaces of a pair of adjoining separator plates. Thepassageway then extends through one or more ports penetrating thethickness of one of the plates thereby fluidly connecting the manifoldto the opposite active surface of that plate, and the contactedelectrode. The ports that penetrate the thickness of one of the plates,are angled ports, such that the fluid flowing from one side of plate tothe opposite side is not directed against any perpendicular surfaces.That is, the surfaces of the ports are not perpendicular to the plane ofthe plates, but are angled and/or curved to reduce turbulence andpressure loss.

[0014] The non-active surfaces of adjoining separator plates in a fuelcell stack can thus cooperate to provide passageways for directing atleast one of the reactant from a respective fuel or oxidant manifold tothe appropriate electrodes. In cases where the non-active surfaces oftwo adjoining separator plates accommodate both the oxidant and fuelreactant streams, the fuel and oxidant reactant streams are, of course,fluidly isolated from each other. Coolant passages may also beconveniently provided between the non-active surfaces of adjoiningseparator plates.

[0015] In other words, the fluid port directs the fluid at an anglebetween 0 degrees and 90 degrees from the direction of fluid flow in thepassageway directly upstream of the fluid path. In this disclosure, 0degrees is defined as being parallel to the direction of the fluid flowin the passageway upstream of the fluid port and 90 degrees is definedas being perpendicular to the direction of the fluid flow in thepassageway upstream of the fluid port. That is, the fluid port walls areshaped so that the fluid flow vectors are not directed against any wallsthat are angled more than 90 degrees from the fluid flow vector.Preferably the effective angle of the fluid port walls is between about20 degrees and about 45 degrees with respect to the direction of thefluid flow in the passageway upstream of the fluid port.

[0016] In a preferred embodiment, the non-active surfaces of adjoiningseparator plates provide fluid passageways for both the fuel and oxidantstreams, which are, of course, fluidly isolated from each other. Thatis, within the electrochemical fuel cell stack:

[0017] at least one of the fuel stream passageways traverses a portionof one of the adjoining non-active surfaces of a pair of the separatorplates, and the at least one fuel stream passageway comprises a fuelfluid port fluidly connecting a portion of the fuel stream passageway onthe non-active surface, with the active surface of one of the pair ofplates;

[0018] at least one of the oxidant stream passageways traverses aportion of one of the adjoining non-active surfaces of a pair of theseparator plates, and the at least one oxidant stream passagewaycomprises an oxidant fluid port fluidly connecting a portion of theoxidant stream passageway on the non-active surface, with the activesurface of the other of the pair of plates; and

[0019] the fuel fluid port and the oxidant fluid port each comprisewalls that are angled more than 0 degrees and less than 90 degrees withrespect to the direction of fluid flow in the respective fuel andoxidant passageways upstream of the respective fluid port.

[0020] In preferred embodiments, to further reduce turbulence the fluidport walls are curved. For example, the fluid port walls may be convex.The fluid port walls may also be curved more than one direction. Forexample, the walls may be curved in both the in-plane and through-planedirections (wherein the “plane” is defined herein as the plane of theactive surface).

[0021] In one embodiment the angled fluid port is in the shape of anelongated slot and is fluidly connected to a plurality of fluid channelsformed in the active surface.

[0022] In any of the above embodiments, the separator plates may be flowfield plates wherein the active surfaces have reactant flow fieldchannels formed therein, for distributing reactant streams from thesupply manifolds across at least a portion of the contacted electrodes.In such cases the angled fluid ports may fluidly connect passageways onthe non-active plate surfaces to reactant flow field channels on theactive plate surface.

[0023] Fuel cell separator plates incorporating the disclosed featuresmay be made from any materials that are suitable for fuel cell separatorplates. Preferred properties for fuel cell separator plate materialsinclude impermeability to reactant fluids, electrical conductivity,chemical compatibility with fuel cell reactant fluids and coolants, andphysical compatibility with the anticipated operating environment,including temperature and the humidity of the reactant streams. Forexample, carbon composites have been disclosed herein as suitablematerials. Expanded graphite composites may also be suitable materials.The disclosed discrete fluid distribution channels may be formed, forexample, by embossing a sheet of expanded graphite material. Compositeplate materials may further comprise a coating to improve one or more ofthe plate's desired properties. Persons skilled in the art willunderstand that the present separator plates may be made from othermaterials that are used to make conventional separator plates, such as,for example, metal.

[0024] When expanded graphite is the material selected for the separatorplates, the fluid ports, in addition to other features of the plate,such as, for example, the fluid passageways, and flow field channels,may be made by embossing a sheet of deformable expanded graphite. A pairof embossing dies may comprise features that cooperate with one anotherto form features such as the fluid ports. When a carbon composite is thematerial selected for the separator plates, the fluid ports and otherfeatures such as the flow field channels and non-active surfacepassageways may be molded.

[0025] The electrochemical fuel cell stack may optionally furthercomprise reactant exhaust manifolds for directing a reactant stream fromone, or preferably more, of the fuel cell electrodes. In preferredembodiments, reactant stream passageways fluidly interconnecting thereactant exhaust manifolds to the electrodes also traverse a portion ofadjoining non-active surfaces of a pair of separator plates and compriseangled exhaust ports fluidly connecting the non-active surface of theplates to the respective active surfaces.

[0026] In further embodiments passages for a coolant may also be formedbetween co-operating non-active surfaces of adjoining anode and cathodeplates, or one or more coolant channels may be formed in the activesurface of at least one of the cathode and/or the anode separatorplates. In an operating stack, a coolant may be actively directedthrough the cooling channels or passages by a pump or fan, oralternatively, the ambient environment may passively absorb the heatgenerated by the electrochemical reaction within the fuel cell stack.

[0027] As mentioned above, passageways for both the fuel and oxidantreactant streams may extend between adjoining non-active surfaces of thesame pair of plates, but the passageways are fluidly isolated from eachother. To improve the sealing around the reactant stream passagewayslocated between adjoining non-active surfaces of the separator plates,the fuel cell stack may further comprise one or more gasket sealsinterposed between the adjoining non-active surfaces. Alternatively, orin addition to employing gasket seals, adjoining separator plates may beadhesively bonded together. To improve the electrical conductivitybetween the adjoining plates, the adhesive is preferably electricallyconductive. Other known methods of bonding and sealing the adjoiningseparator plates may be employed.

[0028] In any of the embodiments of an electrochemical fuel cell stackdescribed above, the manifolds may be selected from various types ofstack manifolds, for example internal manifolds comprising alignedopenings formed in the stacked membrane electrode assemblies andseparator plates, or external manifolds extending from an external edgeface of the fuel cell stack.

[0029] As used herein, adjoining components are components that are incontact with one another, but are not necessarily bonded or adhered toone another. Thus, the terms “adjoin” and “contact” are intended to besynonymous.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 is an illustration of the results of a vectoral flowanalysis for a separator plate that comprises a fluid port with wallsthat are perpendicular to the direction of fluid flow in the passagewayextending from the manifold.

[0031]FIG. 2 is an illustration of the results of a vectoral flowanalysis for a separator plate that comprises a fluid port with wallsthat are angled with respect to the direction of fluid flow in thepassageway extending from the manifold.

[0032]FIG. 3 is a partial three-dimensional section view of a separatorplate that comprises an angled fluid port.

[0033]FIG. 4 is a partial section view of two plates that may used asembossing dies or mold plates for forming the separator plate shown inFIG. 3.

[0034]FIG. 5A is a partial plan view of a separator plate that comprisesa fluid port in the shape of a slot.

[0035]FIG. 5B is a partial section view of the separator plate of FIG.5A.

[0036]FIG. 6 is a partial three-dimensional view of a separator platethat comprises a fluid passage that fluidly connects the non-active andactive surfaces of the plate, wherein the fluid passage is curved in thethrough-plane and in-plane directions.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0037]FIG. 1 is an illustration of the results of a vectoral flowanalysis that depicts the flow vectors of a fluid that is directed frommanifold 10, through passageway 20 on one side of a separator plate (notshown), through port 30, and then to channel 40 on the opposite side ofthe separator plate. In FIG. 1, the bold, solid lines are indicative ofthe outline of the flow passageway. The bold, broken lines in FIG. 1 areindicative of some, but not all, of the transverse edges of thepassageway. In this analysis, passageway 20 corresponds, for example, toa passageway associated with the non-active surface of the separatorplate, and channel 40 corresponds, for example, to a channel associatedwith the active surface of the separator plate. In the example of FIG.1, port 30 comprises walls that are substantially perpendicular to themajor substantially planar surfaces of the separator plate. That is, thewalls of port 30 are oriented substantially 90 degrees with respect tothe direction of fluid flow in passageway 20.

[0038] Known fuel cell separator plates (not shown) that employ bridgesand fluid passageways extending from manifolds to flow field channels onthe active surface of the separator plate provide a substantiallystraight fluid path. That is, the fluid path is substantially parallelto the plane of the active surface, and substantially laminar flow isexpected in the passageway between the manifold and the fluid flow fieldarea. Accordingly, the effect of turbulence between the fluid manifoldsand the flow field area was not a concern with fuels cells usingseparator plates with this design.

[0039] For fuel cell separator plates providing a fluid path like theone shown in FIG. 1, turbulence may be a concern because the turbulenceresults in increased pressure losses. In addition, in solid polymer fuelcells employing “perpendicular” ports like port 30, the fluid exitingport 30 typically impinges directly on the electrode and enters directlyinto the active area where turbulence may have an adverse effect on theelectrode and membrane electrolyte. In particular, empirical data showsthat the portions of the membrane opposite ports like port 30 arelocations where degradation of the membrane is more likely to occur.

[0040]FIG. 2 is an illustration of the results of a vectoral flowanalysis that depicts the flow vectors of a fluid that is directed froma manifold (not shown), through passageway 50 on one side of a separatorplate (not shown), through angled port 60, and then to channel 70 on theopposite side of the separator plate. In this analysis, passageway 50corresponds, for example, to a passageway associated with the non-activesurface of the separator plate, and channel 70 corresponds, for example,to a channel associated with the active surface of the separator plate.In the example of FIG. 2, port 60 comprises walls that are curved andare angled more than 0 degrees and less than 90 degrees with respect tothe direction of fluid flow in passageway 50. In the example of FIG. 2,the effective angle of port 60, with respect to the direction of fluidflow in passageway 50 is about 30 degrees. A comparison of the resultsdepicted in FIGS. 1 and 2 demonstrates a much-reduced amount ofturbulence that was unexpected given the thickness of typical fuel cellseparator plates. To reduce the weight and volume of fuel cell stacks,separator plates are generally made thin. For example, typical fuel cellseparator plates are less than 5 millimeters thick. Accordingly, theoffset is typically small between the passageway (for example,passageway 50) and the flow field channel (for example, channel 70)which are both formed within the thickness of the plate (that is, on thenon-active surface and the active surface, respectively).

[0041]FIG. 3 is a partial three dimensional sectional view of separatorplate 100. The reactant fluid flows generally in the direction of arrow110, from a passageway 120, through port 130 and into channel 140. Thewalls of port 130 are angled with respect to the direction of fluid flowin passageway 120 by an angle of about 20 degrees. Further, the walls ofport 130 are curved in the through plane direction in a convex shape toprovide a sturdier leading edge that is less susceptible to damage.

[0042]FIG. 4 is a partial section detail view of two embossing dies ormold plates that may be employed in cooperation with each other to forman angled port like port 130 in FIG. 3. For example, in the case whereplates 150 and 160 are embossing dies, a compressible formable materialsuch as, expanded graphite, is placed between plates 150 and 160. Whenplates 150 and 160 are pressed together, raised portion 155, forexample, forms passageway 120 and half of port 130, and raised portion165 forms channel 140 and the other half of port 130. Alternatively,when plates 150 and 160 are mold plates, the plates are pressed togetherand then the uncured plate material is injected into the mold, fillingthe void spaces. The uncured plate material is then cured in the mold.After curing, plates 150 and 160 are separated, releasing a molded platecomprising features like those of the plate illustrated in FIG. 3.

[0043]FIG. 5A is a partial plan view of separator plate 200, whichcomprises fluid manifold 210 and flow field area 220 which comprisesreactant channels 230. Fluid is directed from manifold 210 to channels230 via fluid passageway 240 on the opposite surface of the plate (shownin the partial section view in FIG. 5B) and angled fluid port 250 (shownin both FIGS. 5A and 5B). Separator plate 200 further comprises grooves260 and 270 for accommodating seals for fluidly isolating manifold 210and flow field area 220. Section line B-B, in FIG. 5A, indicates thelocation of the section view shown in FIG. 5B. In this example, fluidport 250 is in the shape of an elongated slot that is fluidly connectedto a plurality of channels 230.

[0044] In the embodiment illustrated in FIG. 6, separator plate 300comprises passageway 310, fluid port 320, and flow field channel 330. Inthis embodiment, fluid port 320 curves in both the through-planedirection and the in-plane direction. Like other embodiments disclosedherein, fluid passageway 310, fluid port 320, and flow field channel 330may all be formed by embossing dies or plates, similar to those shown inFIG. 4.

[0045] While particular elements, embodiments and applications of thepresent invention have been shown and described, it will be understood,of course, that the invention is not limited thereto since modificationsmay be made by those skilled in the art without departing from the scopeof the present disclosure, particularly in light of the foregoingteachings.

What is claimed is:
 1. A fuel cell separator plate comprising: (a) anactive surface; (b) an oppositely facing non-active surface; (c) atleast one reactant stream passageway traversing a portion of saidnon-active surface of said separator plate; and (d) a fluid port fluidlyconnecting the portion of said passageway on said non-active surfacewith said active surface of said separator plate, wherein said fluidport comprises walls that are angled more than 0 degrees and less than90 degrees with respect to the direction of fluid flow in saidpassageway upstream of said fluid port.
 2. The separator plate of claim1 wherein said active surface comprises at least one channel fluidlyconnected to said fluid port.
 3. The separator plate of claim 1 whereinsaid fluid port comprises walls that are angled more than about 20degrees and less than about 45 degrees with respect to the direction offluid flow in said passageway upstream of said fluid port.
 4. Theseparator plate of claim 1 wherein said fluid port comprises walls thatare angled about 20 degrees with respect to the direction of fluid flowin said passageway upstream of said fluid port.
 5. The separator plateof claim 1 wherein said fluid port comprises walls that are angled about45 degrees with respect to the direction of fluid flow in saidpassageway upstream of said fluid port.
 6. The separator plate of claim1 wherein said fluid port walls are curved to reduce turbulence withinsaid fluid port.
 7. The separator plate of claim 6 wherein at least oneof said fluid port walls is convex.
 8. The separator plate of claim 6wherein said fluid port walls are further curved both in the in-planeand through-plane directions, wherein said plane is the plane of saidactive surface.
 9. The separator plate of claim 1 wherein said fluidport is in the shape of an elongated slot and is fluidly connected to aplurality of fluid channels formed in said active surface.
 10. Theseparator plate of claim 1 wherein said separator plate is molded andsaid fluid port is formed by a mold.
 11. The separator plate of claim 1wherein said separator plate is embossed and said fluid port is formedby a raised feature on an embossing die.
 12. The separator plate ofclaim 1 wherein said portion of said reactant stream passageway thattraverses said non-active surface of said separator plate comprises agroove formed in said separator plate.
 13. The separator plate of claim1 further comprising coolant passages formed in said non-active surfaceof said separator plate.
 14. The separator plate of claim 1 furthercomprising coolant passages formed in said active surface of saidseparator plate.
 15. The separator plate of claim 1 , further comprisingan internal manifold opening therein, wherein said portion of saidreactant stream passageway that traverses said non-active surface ofsaid separator plate is fluidly connected to said manifold opening. 16.The separator plate of claim 1 , further comprising: (e) an internalreactant supply manifold opening therein; (f) at least one reactantstream supply passageway fluidly connected to said supply manifoldopening and traversing a portion of said non-active surface of saidseparator plate; (g) a fluid supply port fluidly connecting said supplypassageway with said active surface of said separator plate; (h) aninternal reactant exhaust manifold opening therein; (i) at least onereactant stream exhaust passageway fluidly connected to said exhaustmanifold opening and traversing a portion of said non-active surface ofsaid separator plate; and (j) a fluid exhaust port fluidly connectingsaid exhaust passageway with said active surface of said separatorplate, wherein each of said supply and exhaust ports comprise walls thatare angled more than 0 degrees and less than 90 degrees with respect tothe direction of fluid flow in the passageway upstream of respectivesaid port.
 17. A fuel cell separator plate comprising: (a) an anodeplate having an active surface and an oppositely facing non-activesurface; (b) a cathode plate having an active surface and an oppositelyfacing non-active surface adjoining said non-active surface of saidanode plate; (c) fuel stream passageways for supplying a fuel stream tosaid active surface of said anode plate, and oxidant stream passagewaysfor supplying an oxidant stream to said active surface of said cathodeplate, wherein at least one of said fuel or oxidant stream passagewaystraverses a portion of said adjoining non-active surfaces of said anodeand cathode plates; and (d) a fluid port fluidly connecting the portionof said at least one passageway traversing a portion of said adjoiningnon-active surfaces with said active surface of one of said anode andcathode plates, wherein said fluid port comprises walls that are angledmore than 0 degrees and less than 90 degrees with respect to thedirection of fluid flow in said passageway upstream of said fluid port.18. The separator plate of claim 17 wherein said fluid port compriseswalls that are angled more than about 20 degrees and less than about 45degrees with respect to the direction of fluid flow in said passagewayupstream of said fluid port.
 19. The separator plate of claim 17 whereinsaid fluid port comprises walls that are angled about 20 degrees withrespect to the direction of fluid flow in said passageway upstream ofsaid fluid port.
 20. The separator plate of claim 17 wherein said fluidport comprises walls that are angled about 45 degrees with respect tothe direction of fluid flow in said passageway upstream of said fluidport.
 21. The separator plate of claim 17 wherein said fluid port wallsare curved to reduce turbulence within said fluid port.
 22. Theseparator plate of claim 21 wherein at least one of said fluid portwalls is convex.
 23. The separator plate of claim 21 wherein said fluidport walls are further curved both in the in-plane and through-planedirections, wherein said plane is the plane of said active surface. 24.The separator plate of claim 17 wherein said fluid port is fluidlyconnected to at least one fluid channel formed in said active surface.25. The separator plate of claim 17 wherein said fluid port is in theshape of an elongated slot and is fluidly connected to a plurality offluid channels formed in said active surface.
 26. The separator plate ofclaim 17 wherein said portion of said passageway that traverses aportion of said adjoining non-active surfaces of said anode and cathodeplates comprises a groove formed in at least one of said anode andcathode plates.
 27. The separator plate of claim 17 further comprisingcoolant passages formed between cooperating non-active surfaces of saidanode and cathode plates.
 28. The separator plate of claim 17 wherein:at least one of said fuel stream passageways traverses a portion of saidadjoining non-active surfaces of at least one of said anode and cathodeplates, and comprises a fuel fluid port fluidly connecting said fuelstream passageway with said active surface of said anode plate; at leastone of said oxidant stream passageways traverses a portion of saidadjoining non-active surfaces of at least one of said anode and cathodeplates, and comprises an oxidant fluid port fluidly connecting saidoxidant stream passageway with said active surface of said cathodeplate; and said fuel fluid port and said oxidant fluid port eachcomprise walls that are angled more than 0 degrees and less than 90degrees with respect to the direction of fluid flow in the passagewayupstream of respective said fluid port.
 29. The separator plate of claim17 , further comprising: (e) aligned fuel supply manifold openings insaid anode and cathode plates, respectively, fluidly connected to saidfuel stream passageways, wherein at least one of said fuel streampassageways comprises a fuel supply passageway that traverses a portionof the adjoining non-active surface of at least one of said anode andcathode plates; (f) a fuel fluid supply port fluidly connecting saidfuel supply passageway with said active surface of said anode plate; (g)aligned fuel exhaust manifold openings in said anode and cathode plates,respectively, fluidly connected to said fuel stream passageways, whereinat least one of said fuel stream passageways comprises a fuel exhaustpassageway that traverses a portion of the adjoining non-active surfaceof at least one of said anode and cathode plates; and (h) a fuel fluidexhaust port fluidly connecting said active surface of said anode platewith said fuel exhaust passageway, wherein each of said supply andexhaust ports comprise walls that are angled more than 0 degrees andless than 90 degrees with respect to the direction of fluid flow in thepassageway upstream of respective said port.
 30. The separator plate ofclaim 17 , further comprising: (e) aligned oxidant supply manifoldopenings in said anode and cathode plates fluidly connected to saidoxidant stream passageways, wherein at least one of said oxidant streampassageways comprises an oxidant supply passageway that traverses aportion of the adjoining non-active surfaces of at least one of saidanode and cathode plates; (f) an oxidant fluid supply port fluidlyconnecting said oxidant supply passageway with said active surface ofsaid cathode plate; (g) aligned oxidant exhaust manifold openings insaid anode and cathode plates fluidly connected to said oxidant streampassageways, wherein at least one of said oxidant stream passagewayscomprises an oxidant exhaust passageway that traverses a portion of theadjoining non-active surface of at least one of said anode and cathodeplates; and (h) an oxidant fluid exhaust port fluidly connecting saidactive surface of said cathode plate with said oxidant exhaustpassageway, wherein each of said supply and exhaust ports comprise wallsthat are angled more than 0 degrees and less than 90 degrees withrespect to the direction of fluid flow in the passageway upstream ofrespective said port.
 31. The separator plate of claim 17 wherein saidadjoining non-active surfaces of said anode plate and said cathode plateare bonded together.
 32. The separator plate of claim 31 wherein saidadjoining non-active surfaces are bonded together using an electricallyconductive adhesive.